What Are Thrips?
Thrips are tiny, slender insects with fringed wings. They’re hard to spot without a magnifying glass because they’re usually only 1-2 mm long. Despite their small size, they can cause a lot of trouble for plants.
What Damage do Thrips Cause?
Thrips feed by puncturing plant cells and sucking out the contents, which leaves silvery or bronzed streaks on leaves, petals, and fruits. You might also notice black specks (their droppings) and deformed growth on your plants. In greenhouses or indoors, they can be even more of a headache since they thrive in warm environments.
Where Are Thrips Found in the UK?
They’ve been around for a while, but with warmer summers, they're becoming more of a problem. In the UK, common types include:
- Western flower thrips – these are a major pest in greenhouses.
- Onion thrips – often found in leeks, onions, and similar crops.
- Pea thrips – usually outdoors, found in peas and other legumes.
They’re not just outdoors either — indoor plants and greenhouse crops are prime targets.
When Are Thrips Active?
Thrips are most active from spring through early autumn. Indoors, especially in greenhouses, they can be present year-round due to the warmer conditions.
How Do Thrips Spread?
They fly, crawl, and can hitch a ride on new plants. Even wind can carry them from plant to plant. Once they find a host, they multiply quickly. Their life cycle from egg to adult can be as short as two weeks in warm conditions.
How Can You Spot Thrip Infestation?
- Silvery patches or streaks on leaves or petals
- Deformed flowers or fruits
- Tiny black dots (their waste)
- If you shake the plant over white paper, you might see little specks moving — that’s them.
How To Get Rid of Thrips?
You can tackle them in a few ways:
- Introduce natural predators like lacewing larvae or predatory mites.
- Use yellow sticky traps to monitor and reduce their numbers.
- Use thrip nematodes
- Trim and dispose of heavily infested leaves or flowers.
- Keep an eye on humidity — they don’t like moist conditions.
- In severe cases, certain sprays might be needed (always follow local guidelines).
- Attract beneficial insects to the area with an attractant.